Human hepatocellular carcinoma (HCC) is a rapidly increasing type of human cancer, ranked the eighth leading cause of cancer death in the United States. Although early diagnosis and surgical removal is a curative approach for some HCC cases, the majority are not resectable at the time of diagnosis due to lack of efficient early diagnosis and aggressive progression of the disease. Therefore, chemotherapy still remains the primary therapeutic choice for this disease. However, HCC is widely resistant to various cytotoxic antitumor agents, resulting in high patient mortality rates. Aldose reductase-like-1 (ARL-1), a novel protein overexpressed in 54% of human HCC tissues, can efficiently reduce the C13 methyl ketone group of daunorubicin to alcoholic form, daunorubicinol. Daunorubicinol possesses less antitumor activity, but stronger cardiomyopathic toxicity, compared to daunorubicin. Thus, we hypothesize that ARL-1 may represent a novel target to explore a new HCC chemotherapy strategy. This proposal is designed to answer the following questions: Does expression of ARL-1 within HCC tissues result in their drug resistance to anthracyclines? If so, how does this process occur? What is the pharmacokinetics of these agents in tumor tissues with high ARL-1 levels? Within tumors, what is the effect of high ARL-1 levels on the circulating metabolites with strong cardiovascular toxicity? These questions will be addressed through the following specific aims: (1) Determine the in vitro enzymatic activity of ARL-1 in catalyzing the reduction of the anthracyclines, with purified ARL-1 protein; (2) Determine the role of ARL-1 in the intracellular metabolism and antiproliferative activity of the anthracyclines, using ARL-1 gene targeting cell models; and (3) Evaluate the effect of tumor ARL-1 levels on the intratumoral metabolism and antitumor activity of the anthracyclines, using animal tumor models. Human hepatocellular carcinoma (HCC) is the most rapidly increasing type of human cancer in the United States. This disease carries high patient mortality rates, due to its wide resistance to current chemotherapy. Aldose reductase-like-1 (ARL-1) is a novel protein and a potential target for improved HCC chemotherapy treatment. This study will determine the role of ARL-1 in HCC drug resistance and its mechanisms of action, toward the pursuit of reducing HCC patient death. [unreadable] [unreadable] [unreadable]